Introduction
Nested CTEs
Summary
12. Summary

Instruction

Good job! That last query was really challenging!

It's time to wrap things up.

  • It's impossible to put a CTE inside another CTE. However, each CTE can use previously-defined CTEs in the FROM clause.
  • Nested CTEs can be used to compute aggregate functions on several levels.
  • If you need more than just the aggregate result in the outer query, you can use a small subquery.
  • CTEs can also be used to compare two (or more) groups of rows.

Are you ready for a short quiz, then?

Exercise

Click Next exercise to continue.